Furnace



June Z6, 1928.,

INVENTOR Patent .l 26, NZS.,

THOMAS TEEBLES, 0F PITTSBURG, PENNSYLVANI, ASSIGNE T0 JGHN M. HOPWOD, QF DORMNT, PENNSYLVANIA.

FUBNAGE.

Application filed January 12, w27. Serial No. 160,691.

This invention relates to furnaces and more particularl to a system of combustion control for urnaces adapted to use different fuels.

Furnaces such, for example, as those employed in connection witlrblast furnacesfor the pu me. using blast furnace gas as fuel are subject to wide and sometimes sudden variations in the supply thereof,l as a result of variations in the operation of the associated blast furnace or furnaces, and it will be readily 'understood that the operator of such an arrangement has no .control over such a supply. lt is customary 1n times of insnicient supply of such fuel to maintain combustion by feeding an auxilia fuel int/o the furnace in place thereof, an this may be done by such a system as that disclosed in my earlier Patent No.

1,459,072, granted June 19, 1923, wherein the drop in pressure of the steamA enerated, resulting from a drop in gas supp y, is employed to automatically put into operation mechanism for feeding pulverized coal, or other fuel, into the furnace.

Due to the fact that boilers of this-type are normally operated with blast furnace only and the powdered coal is used only for the purpose of making up a deliciency in the gas suptply, it is not ractical to provide dra mechanism, i. e., chimneys, fans or the like, large enough to handle all the products of combustion if the full amount of gas is delivered to the boilers at thesame time that a large amount of auxiliary fuel is being supplied thereto, althou h such a conditlon has hitherto been ossi le as a result of a'full supply of blast urnace. gas being suddenly ria-established after a eriod of small gas supply. In` suchl a case' t e pressure of the steam generated does not rise with sufficient rapidity to cut on' the su ply of auxiliary fuel immediately, with te result that both fuels are/supplied to the boiler in large quantities-at the same time, thus building up a high furnace pressure in the combustion chamber. If the as burners are of the asperating t drawing air from the boiler room un er the inluence of the Afurnace draft and the asperating effec-t of the gas, such pressure may blow the llame out through 'the asperatin air openings, causingv serious injury to t e operator. Aside from this it is very detrimental to any boiler setting totbe operated under such conditions even for a short interval.

An object of this invention is to provide a system of combustion control for furnaces adapted to burn more than a single t@ type of fuel of such construction and ar rangement that the rate of feeding of the para'te fuels thereto will be regulated -in accordance wih the furnace capacity.

A further object is to .rovide a system au for supplylng auxiliary giel, to a furnace 1n time of need of such construction and arrangement that such supply willy be reduced by the re-establishment of the supply of primary fuel thereto. v 7u A still further object is to provide a System of combustion control for use with furnaces employing blastfurnace gas of such character that the supply of auxiliary fuel to the furnace during a period of decienc in the gas sugply thereto will be automatically reoluce by the re-establishment of such 'gas supply.

It 1s customary to suppl a battery of furnaces or boilers with fue from a single source so that a decrease in the supply of such vfuel. affects eve -unit of the battery.

It 'will be apparent t at if one or more of such units lare'cut out under such circumstances, those still in use can still be elfi- 85 ciently operated b the lessened supply of fuel. A still furt er object of this invention is to rovide a. -system of controlling the dow o fuel to the individual units of l a battery of furnaces constructed and ar no ranged to regulate the feeding of fuel to the furnaces in accordance with variations in the supply.

`A still furtherobject is to provide a. com bustion control stem ,of the type set forth 19a which will be re atively sim e 1n construe tion, .and positive and reliab e in operation.

These and other objects which will be apparent to those skilled in this particular art are accomplished by means .of the pres- 10o ent invention which is illustrated -in the accompanying vdrawings lin which Figure 1 is a diagrammatic view showing ai rela'- tive arrangement lof parts combined in accordance with one embodiment of this invention and Fig. 2 is a similar view inv plan illustrating a further formof control adapted t be employed in connection with a batf 'tary of boilers or the like which are subject to 'a varying'supplyof fuel. 11o

The particular embodiment of the present invention which has been chosen for the purposes of illustration is shown in Fig.. 1 in connection with such a system as that described in my above mentioned patent wherein steam generating boilers are adaptedto be normally sup lied with gas from an associated blast turna-ce or furnaces. It will, however, be apparent thatethe present system has a much wider range of application than the particular type of boiler or the particular type of fuel herein described, and that it is equally applicable to any desired type of furnace or fuel. Like the system disclosed in the patent, the present arrangement includes mechanism for supplying an auxiliary fuel such, for example, as powdered coal to the boiler when the pressure of the generated steam drops below a'predetermined point either as a result of the reduction in the available supply of primary fuel, in this case blast furnace gas or cause of an unusually large steam demand. rlhe feeding of the auxiliary fuel is continued as long as it is necessary to produce the required' amount of steam and if .the flow of primary fuel has been low it will be apparent that a sudden resumption in the supply of the lat-ter during feeding of a substantial amount of auxiliary fuel,- will produce a highly undesirable pressure in the combustion chamber. ln order to prevent this .and to` automatically reduce the supply of auailiary fuel as a result of the resumption or increase in the flow of the primary fuel the present invention contemplates the provision of a mechanism which, in this instance, is adapted tobe operated by an increase in furnace pressure, for cutting oll the supply of auxiliary fuel.

The present invention is illustrated as applied to a system similar to the system of my above mentioned patent and including .a furnace 5 having a combustion chamber 6 adapted to be supplied with a combustible mixtureof blast furnace gas and air by a burner 7 of any desired type which is connected to a gas main 8 through a supply line 9 and also connected with a fan 10 for supplying air to the. burner through the air supply line 11. The gas supply pipe 9 has a valve such as the damper 12 adapted to be operated by a regulator 13 responsive to the pressure in the gas main through the medium of a pressure tap 14. The regulator may be of any desired type but is preferably of the type shown in Patent No. 1,338,923, granted to John M. Ho-pwood on May 4, 1920. The air line 11 leading to the burner is rovided with a similar valve 15 adapted to be operated by a similar regulator 16 responsive to the relative pressuresof air and gas flowing to the burner through the medium of the pressure taps 17.

A draft outlet 18 leading from the commovement of the regulator piston is possible after the damper 19 has been fully opened. As illustrated, this includes a lever 21 adapted to be oscillated by the regulator 20 so as to raise and lower a connectin link 22, the upper end of which is conne-cte to a damper operating lever 23 by a lost motion connection such as the pin and slot connection 24. The opposite end of the damper operating lever 23 is connected to a rod 25 extending bedownwardly through a bracket 26 and provided'with a weight 27 at its lower end. A collar or stop 28 is secured to the rod above the bracket. It will be 'apparent that, as suming the damper to be closed, upward movement of the regulator enables lthe weight 27 to rotate the damper toopen posit-ion. When the damper is fully opened the stop 28 will engage the bracket 26 so that the damper will be held in such position and continued upward movement of the regulator, without allee-ting the position of the damper, `is ermitted by the lost motion connection 24 etween the operating link and the damper operating lever; Obviousl ,any type of mechanism can be providedorfaccomplishing the same unction-- The lower end of the piston mechanismof the draft regulator 20 is connected by means of a cable or similar means 29 with one end of a lever 30 pivoted at 31 to a suitable sup port. The opposite'end of the lever 30 1s rovided witha vertically extending link 32 aving aslot 33 adapted to slidably receive a pin 34 secured to a valve controlling lever 35 having a in and slot connection 36 with a link 37 slit ably associated by means of a pin and slot connection 33 with the upper end of a link 39 connected to the frame 40 of a master yregulator preferably constructed as described in Letters Patent No. 1,371,243, granted March 15, 1921 to John M. l-lopwood. The frame 40 is also connected by a cable 41 or the like to the Weighted switch 42 o-an automatic starter 43 adapted to make and break-the circuit of -a motor 44 for driving apulverizer 45 of any desired type. The upperend ofthe slotted link 37 y is connected with a weight46 and the opposite end of the valve operating lever 35 is` connected by a cable or the like 47 with the 'weighted operating lever 48 of an auxiliary fuel controlling valve (notshown) adapted to "be opened and closed so as to control the llow 'ot coal .from a hopper t9 through a chute to the pulverizer. 'lhe particular arrangement ofslotted linlis and levers is similar to that shown inm coending application, Serial No. 54,340ved ept. 3 1925. A second cable 5l connects the cable t7 and leverl 35- with the weighted arm 52 of an air valve53 positioned in the air line 5t leading. from the fan l0`to the ulverized coal burner v55. lt will, ot course, e readily understood that'any well known way of adf justing the relative proportions of fuel and airl maybe employed and that the present drawings are purely diagrammatic in character.

. lit is customer to supply a battery of several urnaces or oilers with fuel from a single .source of supply as illustrated in Fig. 2

wherein a multiplicity of boilers 5 are supplied with gas from` the'single gas main 8. The gas main has the usual damper valve 56 operated by a suitable regulator 57 as is well known in the art'.

' rllhe gas inlet valves 12 are controlled, as above described, by the regulators 13 in response 'to variations in the pressure in the gas supply and the regulators are so adjusted` that individual boilers or-furnaces will be successively cut out, by' closing their gas inlet valve l2, as a result ol a continuing decrease in the pressure of the gas supply. For example, asl the pressure in the as .main 8 falls the `furnace atthe lett in ig. 2 will Ahave its gas inlet valves checked by the associated regulator so as to reduce somewhat .the demand or consumption of fuel and pernaces -are cut back onto the gas main in accordance with .the increase in the supply el y gas therein.

As the supply of blast furnace gas is reduced the regulator 13 shown in Fig. l will check the associated damper l2 so as to reduce the suply `of s to the associated burner and com ustion Chamberland the consequerd. unbalancingof the air controlling regulator 16 causes the valve l5 to be con respondingly checked.v The reduction in the amount of steam generated, resulting lfrom the reduced combustion, operates the mastery regulator 40 through a pressure tap 60 connecting the regulator with a steam header 61 as described in thefabove mentioned Patent No.'1,1t59,072, so that the movable fr, is lowered in such a way as to Iraise the weighted switch 42 ol the automatic starter thus closing the circuit et the motor tt and causing' the latter to start driving'the pulveriZer.- The lost motion or pin and slot connection 38 between the links 37 and 39 and the provisionof the weight 46 attached to the upper end of the link 37 holds the latter stationary during the rst part of the downward movement of the' lower link until after the closing of the motor circuit and a continued downward movement of the lower link 39 so that the motor and pulverizer are given a 4sudicient period of time to reach their lull speed, even where the steam pressure is dropped rapidly and causing a correspondingly rapid lowering of the regulator frame and the associated links, Con- .tinu'ed lowering of the steam pressure and Vthe resulting continued lowerlng of the frame 40 and link 39 eventually take up the slack in the lostl motion connection 38 and pull the link 37 downwardly against the resistance of the associated weight d6., Such low ering of the link 37 lowers the pin and slot connection 36 with the 'adjacent-end of the pivoted auxiliary fuel valve-controllin lever 35 so that the latter is oscillated to t e lett as shown in Fig. l under the induence of the weights associated with the respective valve levers 48 'and 52, thus causing the associated valves to oplen and flow otcoal throng the pu verizer and to the burner 55 and the dow et air the fan to the burner. rllhe operation so ar described is similar to the operation of the mechanism in Patent No. l,t59,072and 'of the various other systems foraccomplishingl the same purpose.v y

- he present invention contemplates the provision of mechanism for automatically reduci the supplyof auxiliary fuel to a boiler in accordance with the resumption of the supply 'of Qprimary fuel thereto so as toY prevent the disadvantages and deterioration resulting ltrein thedow 'ot both-fuels into the turnac'e in large quantities at the same time which occurs .when the suply el primary fuel is resumed ltoo rapid of any immediate and corresondmg increase in the pressure of the steam ing generated. This is accomplished inthe illustrated embodiment of this linvention by employing the urnacepressure to control the auxilia fuel feeding mechanism. Thismay convenienti "bodem, as described,`by lcornuecting the dral regulator 20, which .is operated by the lurnace pressure in the `combustion chamber, with theme'enism tor controlling the supply of auxiliary fuel.. .ln other words, the

presentinvention isarrand so as to limitthe furnace. rassure to ja-manimum such as to prevent v,t e building.. up et .too great a pressure of this l` 'with its accompanyi disadvantages as flovedescribed.

Assumingthat the gas-supply has been reduc and that the steam pressure has consequently fallen to such mentent as to cause a rmit the free.

to permit Sli lll

supply of powdered coal to be delivered to the combustion chamber 6, and assuming that, during existence of such a condition, the supply of gas is suddenly increased by vthe resumption of operation of the associated the amount of combined fuels being fed' greater than safety or eciency permits. By means of the pressure tap 20 the regulator 20 will be moved upwardly and the damper 19 will be fully opened, while the continued upward movement of the regulator 20, as a result of; the excessive furnace pressure, is permitted by the pin and slot connection 24 between the link 22 and the damper operating lever 23. This continued upward movement of the regulator so moves the associated cable 29 as to oscillate the pivote'd lever 30 to the right, as shown in Fig. 1, thus raising the connected link 32 sufficiently to take up the lost motion between the slot 33 and the pin 34 of the coal valve operating lever 35 and cause the latter to be oscillated to the right a distance dependent upon the amount o f furnace pressure, such oscillation being permitted by the pin and slot connection 36. Obviously, this will so shift the valve connecting cables 47 and `51 as to elevate the weighted valve arms 48 and 52, respectively, and so regulate the associated valves as to reduce the rate of; feed of the auxiliary and coordinate the supply thereof with the supply of gas. Assuming that the supply of gas is sufiicientto cause the complete shutting off of the coal supply, as the steam pressure is built up the master regulator is so operated as to permit lowering of the weighted swit ch arm 42 and the cutting out of current to the pulverizer motor 44. This movement of the regulator ,also elevates the associated link 37 so that the slack in the lost motion connection 36 is again taken up and the elements assume the position shown in Fig. 1. The rise of the furnace pressure in the combustion chamber to normal causes the associated regulator I20 to lower the damper connecting link 22 to the position shown in Fig. 1 where its further movement will cause a variation inthe position of the damper in accordance with variations in the furnace pressure and such lowering of the regulator 20 returns the associated lever 30 and link 32 to the position shown in Fig. 1, but it will be apparent that such movement will have no effect upon the valve operating lever 35, due to the fact that Leve-,vae

if y

the regulator 40 and link 37 have previously assumed such a position as to hold the lever in valve closing position, as illustrated.

Obviously, the desired result can be eected by fuel controls operated by conditions other than the particular one described, i. e., furnace pressure. The principal feature is such a control of the fuel supply as to prevent such supply from ever being greater than can be safely accommodated b the particular draft capacity of any particular furnace in operation.

1t will be apparent to those skilled in the art that the present invention can be successfully employed with many dierent types of furnaces using a wide variety of fuels and that various arrangements other than that described can be used.

1t will also be apparent that various changes, additions, substitutions and omissions can be made in the particular arrangement of elements described, all without departing from the spirit of this invention or the scope of the appended claims. What f claim as new and desire to secure by Letters Patent is:

1. The combination with a furnace of means for supplying fuel thereto from a source bf variable supply, means for supplying fuel thereto from a second source and means for regulating the operation of one of said fuel-supply means to prevent the furnace pressure from exceeding a predetermined maximum. l

2. The combination with a furnace adapted to burn a primary fuel of mechanism for supplying an auxiliary fuel thereto and means for controlling the operation of said mechanism in accordance with the furnace pressure.

3. rlhe combination with a steam generating boiler adapted to burn a primary fuel of means for supplying an auxiliary fuel thereto in response to a decrease in steam pressure and means responsive to an increase in the furnace pressure for controlling the supply of auxiliary fuel.

4. rllhe combination with a steam generating boiler adapted to burn a primary fuel .of means for supplying an auxiliary fuel to said boiler in response to a decrease in steam pressure and means for controlling t-he supply of auxiliary fuel to said boiler in accordance with the pressureA in the combustion chamber there'o n 5. The combination in a furnace of mechanism for supplying a primary fuel thereto, mechanism for introducing an auxiliary fuel thereto and means responsive to the furnace pressure for coordinating the operation of said mechanisms.

6. The combination with .a furnace ada ted to burn blast furnace gas of means or supplying an auxiliary fuel thereto when the supply of blast furnace gasfis insuiiicient and means responsive to the furnace pressure for controlling the supply of auxiliary fuel.

7 lThe combination with a furnace of means for supplying a. primary fuel thereto, means for supplying an auxiliary fuel thereto, pressure responsive means for operating said auxiliary fuel .supply and mechanism operated by the furnace pressure for preventing the operation of .said pressure responsive means. i

8. The combination With a steam generating boiler of means for supplying blast furnace gas thereto, mechanism for supplying an auxiliary fuel thereto in response to a decrease in lsteam pressure, draft regulating mechanism responsive to the furnace pressure and means operated by said draft regulfator for controlling the supply of auxiliary 9. The combination With a battery of furnaces of means for supplying fuel thereto from a source of variable supply and means for shutting off one or more of said furnaces in accordance with the reduction in the supply of said fuel.

10. rlhe combination With a battery of furnaces adapted to burn blast furnace gas of means for supplying such gas thereto and means for progressively shutting off said supply from successive furnaces in accordance With a reduction in the supply of said gas.

11. The combination with a battery of furnaces adapted to burn blast furnace gas of a gas main, connections between said main and each of said furnaces, a valve in each of said connections and a regulator associated with each valve and responsive to variations in the pressure in said gas main for progressively closing successive valves in proportion to a reduction in the gas pressure in said main.

12. The combination With a steam generating boiler adapted to burn primary fuel of means for supplying an auxiliaryfuel thereto and means for controlling the supply of auxiliary fuel in accordance With the draft capacity of the furnace. 1

13. The combination Witha steam generating -boiler adapted to burn primary fuel of pressure responsive means-for supplying an auxiliary fuel thereto and means for limiting the .supply of auxiliary fuel in accordance With the draft capacity of the furnace.

14. The combination with a furnace of means for supplying separate fuels thereto and pressure responsive mechanism for limiting the supply of one of said fuels.

15. The combination with a steam generating boiler of means for supplying separate fuels thereto and pressure responsive mechanism independent of the pressure of steam generated for controlling the supply of one of said fuels.

16. The combination With a steam generating furnace of a main burner associated with a source of variable fuel supply, an auxiliary burner, means for supplying fuel to said auxiliary burner in accordance With the steam pressure, and means operated by an increase in the supply offuel to said main burner for reducing the supply of fuel to said auxiliary burner.

1n testlmony whereof, I have hereunto subscribed my name this 11th day of J anuary, 1927.

THOMAS A. PEEBLES. 

